LONG BEACH — A case that began like something out of a film noir story ended far less dramatically Monday, with a 64-year-old Long Beach man quietly pleading no contest to second-degree murder for the 2011 slaying of his infirm mother.

The victim, 87-year-old Dorothy Ellen Armstrong, was found dead at her East Long Beach home on May 5. On her wall hung a lovely portrait, painted when she was a fledgling young model and actress in the 1940 s through the 1960 s, with knife marks cut deep over her heart.

It could have been the plot synopsis for one of her movie or TV roles, but it was how she lived, and died, at the hands of her son, Douglas Fredrick.

Fredrick entered his no-contest plea - considered the same as a guilty plea in criminal court - before Long Beach Superior Court Judge Gary Ferrari, who immediately sentenced the defendant to 16 years to life in prison. He must serve the base term of 16 years before be can be considered eligible for parole, and he waived all rights to appeal the sentence and conviction, Deputy District Attorney Carol Rose explained.

Rose, and Long Beach Police Department Homicide detectives who investigated the case, said Fredrick killed his mother after she moved from an assisted living center back into the East Long Beach home the pair shared. He grew to resent caring for his mom, and he slashed the portrait two days before killing her, on the same day he was called to the assisted living center to pick up her belongings, authorities said.

When police were called to the home in the 3500 block of Los Coyotes Diagonal on May 5, they found the victim dead in her bed with her throat slashed.

Fredrick told officers he went to his mom's room that day after he heard a gurgling sound.

"He had two different stories," Rose said. "First he said she did it to herself and that when he tried to remove the blade he accidentally pushed it in deeper. ... (Later) he confessed."

The victim was born Dorothy Ellen Partington, and that was the stage name the New York native used when she worked as an actress and model. There are no starring roles listed on IMDB, but the online database for movies and TV shows notes she appeared in a film with Richard Burton in 1960, "Ice Palace," and had a role in an episode of "Lawman" in 1959.

Married twice, she had two sons, Fredrick and his half-brother, William Armstrong.

Armstrong addressed the court Monday, before sentencing, and talked about the pain, remorse and anguish he has felt since his mother's murder. He said he never would have imagined having to address the court for such a matter, and that try as he might to memorize his statement and keep composed he couldn't completely prepare himself for the rush of emotion he felt standing before the judge.

"The words can't stay in your head because they hurt too much," Armstrong said, his eyes brimming with tears.

"I vowed to myself that in the future, if I cry a tear, I cry one for mother, If I say a prayer, I say one for mother," he added, before saying he felt sorrow for everyone in the family, including Fredrick.

As he spoke, Fredrick bowed his head. The defendant, who was handcuffed and shackled and who wore yellow and blue Los Angeles County Jail inmate infirmary garb, sounded and appeared medicated when he spoke Monday.

A diagnostic analysis done last year by California Department of Correction and Rehabilitation doctors found him mentally fit to stand trial, paving the way for a charge of first-degree murder.

Fredrick opted, against the advice of his attorney, to plead to the lesser count of second-degree murder, and an offer of 15 years to life in prison plus an additional year for personal use of a weapon, to avoid a trial and, potentially, a harsher sentence.

"I will not join in the plea because (Fredrick) has chosen, against my advice, to take advantage of this offer," Public Defender Carolyn Disabatino told the court, noting not all of the discovery in the case had been turned over and the defense investigation wasn't completed.

After she spoke, her client addressed the court and expressed remorse for his actions.

"I am terribly sorry for the events that took place last May," he said softly. "I would like to express my (remorse) to my brother ... and the rest of my family."